What does Charis show Felix at her cottage and what does Felix explain to her?

Charis shows Felix all of the unmailed letters that were returned with the possessions that Gabriel left onboard the troop ship. The many letters that Gabriel started to write to Charis are unfinished. Most of them have nothing more than "Dear Charis." Felix explains that Gabriel had wanted to write to her, but he simply did not know how because he had never been much of a writer.